Transformer Oil-Key Insulation and Cooling Medium
Transformer oil serves as the primary insulation and cooling medium in oil-immersed transformers. Its dielectric strength and chemical composition directly impact transformer performance. Even trace amounts of moisture or impurities can degrade insulation properties, while exposure to oxygen at high temperatures accelerates oxidation. Thus, oil filtration is essential during transformer installation.
To safeguard operational safety, routine oil sampling and chemical analysis are required for in-service distribution transformers, with a mandatory testing cycle of at least once every 3 years.
Key Oil Quality Indicators & Maintenance Measures
1. Acid Value
Definition: Measures acidic compounds (primarily organic acids) in oil, expressed as mg KOH required to neutralize 1g of oil.
Significance:
For new oil: Reflects refining quality (dominated by naphthenic acids).
For used oil: Indicates aging (generates fatty acids via oxidation).
Action: Critical for determining oil serviceability.
2. Water-Soluble Acids
Limit: pH < 4.2.
Causes: Oil aging or contamination.
Solutions:
Investigate via repeated tests and acid value comparison.
Recondition oil or replace if economically viable.
3. Breakdown Voltage
Limit: <20 kV.
Causes: Excessive moisture or particulate contamination.
Solutions:Use ZJB vacuum oil purifiers (post-treatment target: >50 kV) or replace oil.
4. Flash Point
Limit: <130°C or ≥5°C drop from prior tests.
Causes: Local overheating or incorrect oil mixing.
Solutions:Troubleshoot overheating; degas with vacuum purifiers or replace oil.
5. Visual Appearance
Abnormal Signs: Cloudiness, suspended particles, or darkening.
Causes & Actions:
Whitish haze: Check moisture content.
Black particles/charred odor: Investigate internal arcing (correlate with other tests).
Darkening: Monitor aging rate (combine with acid value analysis and temperature checks).
Proactive Maintenance
For moisture/particulates: Prioritize vacuum filtration (e.g., ZJB series).
For oxidation/aging: Consider oil regeneration or replacement.
For critical units: Implement real-time oil monitoring (temperature, dissolved gas).
Technical Note: Adherence to IEC 60296 standards ensures optimal dielectric performance and extended transformer lifespan.
To safeguard operational safety, routine oil sampling and chemical analysis are required for in-service distribution transformers, with a mandatory testing cycle of at least once every 3 years.
Key Oil Quality Indicators & Maintenance Measures
1. Acid Value
Definition: Measures acidic compounds (primarily organic acids) in oil, expressed as mg KOH required to neutralize 1g of oil.
Significance:
For new oil: Reflects refining quality (dominated by naphthenic acids).
For used oil: Indicates aging (generates fatty acids via oxidation).
Action: Critical for determining oil serviceability.
2. Water-Soluble Acids
Limit: pH < 4.2.
Causes: Oil aging or contamination.
Solutions:
Investigate via repeated tests and acid value comparison.
Recondition oil or replace if economically viable.
3. Breakdown Voltage
Limit: <20 kV.
Causes: Excessive moisture or particulate contamination.
Solutions:Use ZJB vacuum oil purifiers (post-treatment target: >50 kV) or replace oil.
4. Flash Point
Limit: <130°C or ≥5°C drop from prior tests.
Causes: Local overheating or incorrect oil mixing.
Solutions:Troubleshoot overheating; degas with vacuum purifiers or replace oil.
5. Visual Appearance
Abnormal Signs: Cloudiness, suspended particles, or darkening.
Causes & Actions:
Whitish haze: Check moisture content.
Black particles/charred odor: Investigate internal arcing (correlate with other tests).
Darkening: Monitor aging rate (combine with acid value analysis and temperature checks).
Proactive Maintenance
For moisture/particulates: Prioritize vacuum filtration (e.g., ZJB series).
For oxidation/aging: Consider oil regeneration or replacement.
For critical units: Implement real-time oil monitoring (temperature, dissolved gas).
Technical Note: Adherence to IEC 60296 standards ensures optimal dielectric performance and extended transformer lifespan.
